Note : Though in theory other fuel types are possible, the
Diesel engine, for maintenance and time resistance reasons,
is used exclusively with heavy oils, mineral (from petrol) or,
just from a short time, partially biologic (colza as addictive).
The Stirling engine, as the cylinder is heated externally, can use any type of stuff that can give heat, in particular:
mineral oils (gasoline or diesel), biologic liquids
(alcohol, various oils), solids (coal, paper, wood, disposal,
excrements) e gaseous
( methane butane/propane gases, hydrogen) and at the end direct
energy (sun).

As the combustion is slow relating to Diesel one (that is
compelled to burn the fuel in less an half a turn of the
engine) this is a complete mode, that means it uses completely the energetic
properties of the fuel. In the Diesel engine a part of
the energetic properties is dissipated to create heavy and
complex compounds and another part is not used because the combustione
is partial. In particular, the combustion of a pure
hydrocarbon (HyCx,) where x and y are an appropriated number of carbon and hydrogenum athoms) + O2 (air oxygenum) if it is complete gives CO2 (carbon dioxide) e H2O (water) , on the contrary in incomplete mode it gives H2O CO2e
CO (carbon monoxide, highly poisonous). The CO is dispersed in the air,
and it is impossible to burn it further to give the remaining missing
part of CO2 , consequently it is wasted also the energy that
would be available in this further step.

BTW: The CO2 (carbob
oxide), if from one side is the main cause of the greenhouse
effect, on the other it is very easy to recycle, it is sufficient to
plant more trees!
If the energetic efficiency (output energy/ given energy)
is about the double for the Stirling engine vs. the diesel one,
more high is the ratio: output energy /given resources (as weight).

More, you are not obliged to use just only type of fuel with Stirling engines.Let's see some and their advantages:

The combustion products are that generated in any case by the incinerator.

Paper, wood and derivatives

Low or nil

Recyclable cinders for agricolture.

Solar energy

Nil

No combustion, no product.

As you can see, the Stirling engine is absolutely ecological.
With an impact on the environment from low to nil, it should
replace Diesel engine in all the fields, excluded
perhaps automobilistic one where is requested an high capacity of
acceleration.
In
particular:Electric power
generation in the electro-thermic vaults and power back-up systems of
little as of high power.
Earth moving machines and alike. Not electrified railways.
Irrigating pumps and devices for a continuous use at less or more
constant speed. Etc.etc..

The informations are not few and nowadays the
industry offers engines for every use. It is sufficient surfing
internet to have an idea.Try on
Google the key (double quote included) "Stirling
motors" You will get more then 14000 sites in english and
many in all the languages.
To substitute the Diesel engines in the electro-thermic vaults actually
in function would keep us safe from energetic crises and could
make the bill for electricity a little lighter, giving a little
better chances to industries and families.